This invention relates to a tape loading device and, more particularly, to a tape loading device adapted for a video tape recorder, for example, of 8 mm type.
Recently, a 8 mm video tape recorder (hereinafter referred to as "a VTR") which used a magnetic tape having 8 mm of width has been developed as a VTR.
This 8 mm VTR has large advantages due to the use of narrow (8 mm) magnetic tape, and its cassette, therefore, has substantially the same size (95 mm.times.62.5 mm.times.15 mm) as a compact audio cassette, thereby having reduced size and the weight.
Various sorts of tape loading types in this 8 mm VTR were heretofore considered, and a U-shaped loading type in which the tape is wound substantially in a U-shape on a rotary head cylinder is representative.
FIGS. 1 to 3 show a conventional tape loading device of U-shaped loading type. FIG. 1 is the initial state before loading, FIG. 2 is the intermediate state of loading, and FIG. 3 is the completed state of loading.
In FIGS. 1 to 3, reference numeral 1 denotes a tape cassette. A magnetic tape 2 wound on a supply side reel and a takeup side reel is contained in the cassette 1. This tape 2 is exposed in the recess formed on the front surface of the case. The cassette 1 is mounted as shown in FIG. 1 in the state that the loading device is disposed in the initial state.
This loading device draws the tape 2 from the mounted cassette 1 and winds the tape 2 on a rotary head cylinder 10, and the loading device is constructed as below.
In FIGS. 1 to 3, reference numeral 11 denotes a guide rail provided to surround the outer periphery of the head cylinder 10. A guide slot 12 is formed over the entire length of the upper surface of the guide rail 11.
Reference numeral 13 designates a movable element supported onto the guide rail 11 and slidably moving on the guide rail 10. Two large and small guide rollers 14 and 15 are stood longitudinally on the element 13. Reference numeral 16 depicts a loading ring provided at the lower side of the guide rail 11. The ring 16 is rotatably driven by a drive mechanism, not shown.
The element 13 is coupled through the guide slot 12 of the guide rail 11 with the ring 16, and moves on the rail 11 in the loading direction by the rotation of the ring 16. The element 13 is disposed at the initial position opposed to the mounting position of the cassette 1 as shown in FIG. 1 in the initial state. When the cassette 1 is mounted in this initial state, two rollers 14 and 15 on the element 13 become engaged within the exposed tape of the cassette 1.
When the ring 16 is rotated in a direction of the arrow as shown in FIG. 2 in the state that the cassette 1 is mounted in this manner, the element 13 moves on the rail 11 in the rotating direction of the ring 16, i.e., in the loading direction, the tape 2 is drawn by the large-diameter guide roller 14 at the front side of the element, and drawn from the cassette 1. This tape 2 is wound on the cylinder 10 upon moving of the element 13.
An arcuate movable member 17 which moves reversely to the rotating direction of the ring 16 by a drive mechanism, not shown, is provided outside the ring 16. A pinch roller 19 for pressing the tape 2 on a capstan 18 is provided at the end of the member 17. The roller 19 is disposed inside the exposed tape of the cassette 1 mounted in the initial state, moves the member 17 in a reverse direction to the loading direction upon rotation of the ring 15 in the loading direction, thereby moving the tape 2 while pushing the tape 2 toward the capstan 18 side.
First and second tape guide pins 20a and 20b are tiltably provided at the first rear position from the previous position disposed at a suitable interval with respect to the loading direction from the element 13 on the ring 16, and the second rear position is further rear than the first rear position. The pins 20a and 20b are, as shown in FIG. 4, contained tiltably in a guide pin container 21 formed under the rail 11, drawn from the container 21 upon rotating of the ring 15 in the loading direction, fed under the tape 2 pressed to the capstan 18 side, and kept erect by the tensions of springs 201, 202, as shown in FIGS. 5 and 6.
The guide pins 20a and 20b are introduced into the slots 12 of the rail 11 upon rotating of the ring 16, and moved in the slot 12 in the state that the upper end side of the pins are projected from the rail 11.
Reference numeral 23 designates a guide pin engaging plate having guide pin engaging portions 23a and 23b at both ends in such a manner that the first guide pin engaging portion 23a of loading direction side of the engaging portions 23a and 23b is disposed at the position lower than the other second guide pin engaging portion 23b.
On the other hand, the preceding guide pin 20a of the loading direction side of the pins 20a and 20b is formed shorter than the following guide pin 20b. This pin 20a is fed under the second guide pin engaging portion 23b, and engaged with the first engaging portion 23a when the element 12 arrives at the loading end position. The following pin 20b is engaged with the second engaging portion 23b when the element 13 arrives at the loading end position.
The heights of the rollers 14 and 15 on the element 13 are lower than both of the engaging portions 23a and 23b. Therefore, the element 13 is moved under the engaging portions 23a and 23b to the loading end position.
The tap 2 thus loaded is wound, as shown in FIG. 3, from the feeding side of the cassette 1 between the pinch roller 19 and the capstan 18 onto the outer periphery of the cylinder 10, separated from the cylinder 10, folded at the guide roller 14 of the front side of the element, guided by the roller 15 of the rear side of the element, and the pins 20a and 20b, and fed to the takeup side of the cassette 1.
Reference numerals 24 and 25 designate stationary guide pins or rollers, and reference numeral 25 denotes a control head.
The VTR records and reproduces while rotating the cylinder 10 in the reverse direction to the tape feeding direction as shown by an arrow in FIG. 3.
However, since the above-mentioned conventional tape loading device mounts the pins 20a and 20b guided in the state separated from the cylinder 10 at the folding side of the loaded tape 2 on the ring 15 to erect by the tensions of the springs 201 and 202 after passing under the tape 2 fed to the capstan 18 side the ring 16, the structure for mounting the ring 16 on the pins 20a and 20b is complicated. Further, in the loading device for erecting the pins 20a and 20b by the tensions of the springs 201 and 202, the pins 20a and 20b are tilted by the tension of the tape 2 at recording and reproducing time if the pins 20a and 20b are supported in the erected state by the tensions of the springs even after loading. Thus, it is necessary to provide the guide pin engaging plate 23 for engaging the pins 20a and 20b in the loading completed state as described above. Therefore, the conventional loading device has disadvantages that the structure is very complicated and troublesome in assembling.
Moreover, the guide rollers 14 and 15 provided on the element 13 are necessarily mounted adjustable in height on the guide roller mounts so as to accurately match the height of the rollers to the position of the tape.
FIG. 8 shows the mounting structure of the conventional guide rollers. Reference numeral 81 denotes a guide roller mounting portion (e.g., a rail laid along the drawing direction of the tape), and a roller shaft inserting hole 82 is formed at the mounting portion 81. The hole 82 restricts the attitude of a guide roller 83, and when the roller 83 is mounted vertically, the hole 82 is formed vertically.
Reference numeral 84 designates a roller shaft of the roller 83. A pair of upper and lower flanges 85a and 85b are secured to the upper end and to the intermediate portion of the roller shaft 84, and the roller 83 is interposed between the flanges 85a and 85b to be rotatably supported by the shaft 84.
Further, male threads 84a are formed on the lower portion of the lower flange 85b of the shaft 84, and female threads 82a to be engaged with the male threads 84a of the shaft 84 are formed on the upper end of the hole 82.
Reference numeral 86 depicts an elastic ring interposed between the lower surface of the lower flange 85b and the upper surface of the guide roller mounting portion 81. The shaft 84 is inserted into the hole 82 at the shaft of the lower side of the threads 84a. And the threads 84a is thrusted into the female threads 82a of the hole 82, thereby mounting on the mounting portion 81.
This guide roller mounting structure is provided to regulate the height of the roller 83 by turning the shaft 84 mounted on the mounting portion 81 by engaging the threads 84a with the threads 82a. When the shaft 84 is turned in the clamping direction, the shaft 84 is drawn to the ring 85 by the lower flange 85 while compressing the ring 86, whereas when the shaft 84 is turned in the reverse direction, the shaft 84 lifts the lower flange 85 by the elastic force of the ring 86. Thus, the interval H between the lower flange 85 of the shaft 84 and the mounting portion 81 is regulated to adjust the height of the roller 83.
Reference numeral 87 designates a clamping screw for clamping the lower end of the shaft 84, and the height-regulated roller 84 is securely fixed in height by securing the shaft 84 by clamping the screw 87.
When the roller is mounted adjustably in height, it is desirable to increase the engaging length between the roller shaft inserting hole of the guide roller mounting portion side and the roller shaft of the guide roller as long as possible so as to correctly hold the attitude of the roller.
However, since the clamp for drawing the roller shaft 84 to the guide roller mounting portion 81 is constructed to provide the male threads 84a at the roller shaft 84 and the female threads 82a to be engaged with the male threads 84a at the upper end of the roller shaft inserting hole 82 of the guide roller mounting portion 81 side in the above-mentioned conventional guide roller mounting structure, the length L1 of the effective portion for holding the attitude of the roller shaft 84 is shortened by the length L2 of the female threads 82a with respect to the inserting length L of the roller shaft 84 into the hole 82 (Since "a fluctuation" exists in the engaging portion between the male threads 84a and the female threads 82a, the engaging portion does not have the attitude holding action of the roller shaft 84.).
Thus, in the above-described conventional guide roller mounting structure, the angle of the roller shaft 84 with respect to the guide roller mounting portion 81 might slightly become misaligned. Thus, the conventional structure has a problem that the attitude accuracy of the guide roller 83 supported by the roller shaft 84 does not have reliability. If the length of the female threads 82a and the length of the male threads 84a are increased in the above-mentioned conventional guide, the length L1 of the effective portion for holding the attitude of the roller shaft 84 is increased and will more accurately hold the correct attitude of the roller shaft 84, but to this end the thickness of the guide roller mounting portion 81 must be increased. Thus, if the thickness of the guide roller mounting portion 81 is limited, it is impossible to increase the length L1 of the effective portion for holding the attitude of the roller shaft 84 by increasing the length of the female threads 82a and the length of the male threads 84a.
Accordingly, the conventional tape loading device has difficulties in the mounting structure of the tape guide roller which may cause the tape guide operation is to be disturbed.